Threatened Neotropical mollusks: analysis of shape differences in three endemic snails from High Paraná River by geometric morphometrics

Abstract

Variation in shape among a living and 2 extinct aquatic snails of the genus Aylacostoma, using a geometric morphometric method of thin plate splines and multivariate analysis was investigated. The analysis was performed to evaluate the diagnostic capability of this method and to explore shell shape differences, due to the lack of other data, in an attempt to answer why only 1 of the species persisted in the wild. Sixteen landmarks in a bi-dimensional space for 32 shells of type, paratype and reference specimens deposited in museums of Argentina were defined. Analysis was successful in assigning individual specimens to particular species. Statistically significant differences in last whorl, aperture, and spire were found for the first 4 non-uniform components explaining an 85% of local variation observed. Differences could be related to a differential use of habitat and/or to the degree of exposure to water current. More globose shell found in the extinct species could be associated to habitats and substrata with the highest water currents, whereas the more stylized shell in the third species could be related to a preference for more protected habitats, like those where it presently occurs.

Insights into the Evolutionary History of an Extinct South American Freshwater Snail Based on Historical DNA

“…brunneum has dark brown shells with alternating lighter bands, delicately decorated with minute, dark reddish brown, regularly spaced spiral spots [13]. Moreover, the present results complement those of Vogler et al [70] who conducted a geometric morphometric analysis of available museum material for A . guaraniticum , A .…”

A phylogeographical perspective on theex situconservation ofAylacostoma(Thiaridae, Gastropoda) from the High Paraná River (Argentina-Paraguay)

“…To our knowledge, conservation strategies in South America have been adopted only for the native parthenogenetic freshwater gastropod Aylacostoma (Thiaridae) from the High Paraná River (Argentina–Paraguay) in the context of a conservation breeding programme, known as the ‘ Aylacostoma Project’ (Vogler et al ., ). This ex situ programme was established in the 1990s accompanying the initial filling stages of the Yacyretá Reservoir (Argentina–Paraguay) which flooded the area of the Yacyretá–Apipé rapids where three Aylacostoma species had been recorded: Aylacostoma guaraniticum (Hylton Scott, ), Aylacostoma stigmaticum Hylton Scott, and Aylacostoma chloroticum Hylton Scott, (Peso, Molina & Costigliolo Rojas, ; Peso, Costigliolo Rojas & Molina, ; Vogler, , ; Vogler et al ., , ). This conservation effort is being conducted by the Universidad Nacional de Misiones (UNaM; Posadas, Argentina), in conjunction with the Museo Argentino de Ciencias Naturales (MACN; Buenos Aires, Argentina), and is supported by the Entidad Binacional Yacyretá (EBY; Argentina–Paraguay) (Vogler, ).…”

Application of Shape Analyses to Recording Structures of Marine Organisms for Stock Discrimination and Taxonomic Purposes

“…The GM-based methods are widely applied to investigate variation in the shape of gastropod shells. The main fields of application include the study of intraspecific variability (Vuolo et al, 2011;Madeira et al, 2012;Moneva et al, 2012b;Sepúlveda and Ibáñez, 2012;Vogler et al, 2012;Avaca et al, 2013;Camama et al, 2014;Jamasali et al, 2014;Sobrepeña and Demayo, 2014;Cazenave and Zanatta, 2016;Zhao et al, 2019;Tuset et al, 2020) and assessment of environmental impacts (Sepúlveda and Ibáñez, 2012;Vogler et al, 2012;Vasallo et al, 2013;Camama et al, 2014;Cazenave and Zanatta, 2016;Amini-Yekta et al, 2019;Zhao et al, 2019), including the effect of pollution (Márquez et al, 2011;Abdelhady, 2016;Primost et al, 2016). Nevertheless, GM was also used for identification of mollusks (Doyle et al, 2018), evaluation of interspecific variability (Dommergues et al, 2003;Carvajal-Rodríguez et al, 2005;Vuolo et al, 2011;Cruz et al, 2012;Vogler et al, 2012;Silos et al, 2014;Becker et al, 2016;Miller, 2016), ontogenetic and individual variation (Moneva et al, 2012a;Avaca et al, 2013;Sobrepeña and Demayo, 2014), and to characterize phylogenetic relationships (Smith and Hendricks, 2013;…”